Field of the Invention
The present invention relates to a connecting device for connecting a conveying carriage to a drive chain, to a conveying carriage and to a conveyor system.
Description of the Related Art
In conveyor technology, use if often made of conveying carriages that are moved on rails along a conveying path to transport goods to be conveyed. In sorting plants, the conveying carriages may each have a conveyor belt as a supporting surface for the conveyed goods, wherein the belt conveying direction of the conveyor belt may extend transversely to the direction of movement of the conveying carriage along the rails. Such sorting plants are also called “cross-belt sorters”. By operating the conveyor belt at a desired position of the conveying carriage in the sorting plant, the conveyed goods can be thrown off or discharged to the left or to the right transversely to the direction of movement of the conveying carriage.
Sorting plants, in which the conveying carriages are moved substantially in the horizontal plane, are also referred to as “horizontal sorters”. In such conveyor systems, the rails are arranged substantially in the horizontal plane, and a drive chain, usually made of elastomeric material, is arranged along the conveying path and guided following the course of the rails. “Arranged substantially in the horizontal plane” means that the conveying path or rails may also have ascents and/or descents. The drive chain is usually arranged and guided below the rails and, during operation of the conveyor system, is circumferentially constantly in motion. To move the conveying carriages on the rails along the conveying path, the conveying carriages are connected to the drive chain via connecting devices. Here, the problem arises that the position and orientation of the conveying carriage and the drive chain relative to each other along the conveying path is variable. This is especially the case in curves and in ascending/descending sections of the conveying path due to the polygon effect, since the guide rollers of the conveying carriage, in contrast to the drive chain, do not run on or off in a circular way, so that angulation of the conveying carriage is the result. Thereby, the conveying carriage moves on a polygon with different numbers of chords according to the radius of the rail course. In addition, the attachment point of the drive chain always precedes the attachment point of the conveying carriage. Furthermore, this can be caused by mounting inaccuracies or tolerances.
In order to allow a certain amount of change of the position and orientation of the conveying carriage and of the drive chain relative to each other, complex structures consisting of a plurality of connecting members and joints have been used as connecting devices so far. This leads to a complicated assembly of the conveyor system and to high costs of the connecting devices.
It is therefore an object of the present invention to provide a connecting device as well as a conveying carriage and a conveyor system, which are simple to manufacture and to assemble.